Comparison of NDVI, Response Index, and CV, in Corn, Sorghum, and Wheat from GreenSeeker and Crop Circle Hand-Held Active Sensors

Drew Tucker

GRA Agronomy Department, Kansas State University

Overview of GreenSeeker and Crop Circle Hand Held Active Sensors

• GreenSeeker sensor wavelengths are approximately 660 and 770 nm.

• The field of view at 1 meter from the target is approximately 1 cm by 61 cm wide.

• Crop Circle sensor wavelengths are approximately 550 and 880 nm.

• The field of view at 1 meter from the target is approximately 11 cm by 54 cm wide.

Research Objectives

• To see how NDVI, Response Index, and CV correlates in Corn, Sorghum, and Wheat between the GreenSeeker and Crop Circle hand held active sensors throughout the growing season.

Materials and Methods

• Several Nitrogen field experiments were conducted during the 2006-2008 growing seasons on Corn, Sorghum, and Wheat.

• NDVI, Response Index, and CV from each treatment was collected and averaged.

• The sensors always sensed the same sampling area at the same height above the target at close sensing time intervals to give as true as a comparison as possible.

Comparison of GS NDVI and CC NDVI in Corn.

y = 1.2185x - 0.0438

R2 = 0.79

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Comparison of GS RI and CC RI in Corn.

y = 1.2694x - 0.2656

R2 = 0.57

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Comparison of GS CV and CC CV in Corn.

y = 2.0024x - 3.4394

R2 = 0.77

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CC CV

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Field of view

CV readings

Avg. NDVISensor noise?

CV in 1 m of rowCV per plotCV in 1 m of rowCV per plot

CV in 1 m of rowCV per plotCV in 1 m of rowCV per plot

Comparison of GS NDVI and CC NDVI in Sorghum.

y = 1.484x - 0.2317

R2 = 0.95

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Comparison of GS RI and CC RI in Sorghum.

y = 1.4243x - 0.4314

R2 = 0.85

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Comparison of GS CV and CC CV in Sorghum.

y = 2.4398x - 6.8625

R2 = 0.87

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CC CV

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Comparison of GS NDVI and CC NDVI in Wheat.

y = 1.6436x - 0.333

R2 = 0.97

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Comparison of GS RI and CC RI in Wheat.

y = 1.3698x - 0.3678

R2 = 0.79

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Comparison of GS CV and CC CV in Wheat.

y = 1.6062x - 0.0817

R2 = 0.48

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Conclusions

• NDVI was very strong correlated in sorghum and wheat, while still maintaining a relationship in corn.

• Response Index was very strongly correlated in sorghum and wheat, however, in corn this relationship was not very good.

• CV correlations were very good in sorghum and corn, however, in wheat this relationship was not very good.

• The GreenSeeker sensor seems to have a wider working range and more sensitivity in detecting nitrogen stress especially early in the growing season.

• The Crop Circle sensor and the GreenSeeker sensor both seem to saturate at the same time.

• Due to the observed differences, separate sensor recommendations need to be developed.